推荐铁路列车运行噪声几何发散损失计算采用偶极子指向性特性的理论计算公式或简化公式。
It recommends that the calculation of geometrical spreading loss of running trains noise adopt the theories calculation formula or the simplified formula of directional characteristic of dipole.
铁路列车运行噪声的水平指向性是铁路列车噪声辐射的重要特性之一。
The horizontal direction of train running noise is a important character of train radiating noise.
根据基本声学理论，分析具有单极子、中间和偶极子三种指向性的有限长线声源的几何发散损失特性。
Based on the theory of acoustics, this paper analyzes the character of geometrical spreading loss of finite line sound source on three types of directivity-monopole, intermediate pole and dipole.
超声波具有指向性好，在水中衰减小，束射特性优良。
Ultrasonic has a good pointing, the attenuation in water is small, beam radio feature fine.
超声波具有指向性好，在水中衰减小，束射特性优良。
Ultrasonic has a good pointing, the attenuation in water is small, beam radio feature fine.
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